Which of the following cities has a directly elected mayor?

In the UK, some cities and combined authorities have chosen to have a system with a directly elected executive mayor, who has significant powers and is accountable directly to the electorate. London was one of the first and is the most well-known example. Other major cities like Manchester, Liverpool, and Bristol also have directly elected mayors. This is different from the traditional system where a council is run by a 'leader' who is chosen from among the elected councillors, or a ceremonial 'mayor' with no executive power.